Coating compositions comprising a colloid and a polyoxyalkylene ether of a monohydric alcohol containing more than two alkyl side chains

ABSTRACT

A coating composition and a photographic support coated therewith, said coating composition comprising a water-permeable colloid and a coating aid comprising a polyoxyalkylene ether of a primary monohydric saturated aliphatic alcohol containing more than two alkyl side chains, said alcohol having the molecular configuration of an alcohol produced by the oxo process, said ether containing from 2 to 20 oxyalkylene groups per mole.

United States Patent Inventors George M. Gantz Upper Saddle River, N.J.;E. Scudder Mackey, Binghamton, N.Y.; Raymond L. Mayhew, Summit, NJ.Appl. No. 625,035 Filed Mar. 22, 1967 Patented Nov. 2, 1971 Assignee GAFCorporation New York, N.Y.

COATING COMPOSITIONS COMPRISING A COLLOID AND A POLYOXYALKYLENE ETHER OFA MONOl-IYDRIC ALCOHOL CONTAINING MORE THAN TWO ALKYL SIDE CHAINS [56]References Cited UNITED STATES PATENTS 2,965,678 12/1960 Sundberg et a1.260/638 2,768,894 10/1956 Harriman 96/94 Primary Examiner-J. TravisBrown Attorneys-George L. Tone, Samson B, Leavitt, Homer J.

Bridger, Martin A. Levitin, Walter C. Kehm and Robert H. Zappert COATINGCOMPOSITIONS COMPRISING A COLLOID AND A POLYOXYALKYLENE ETHER OF AMONOHYDRIC ALCOHOL CONTAINING MORE THAN TWO ALKYL SIDE CHAINS Thisinvention relates to coating compositions comprising a water-permeablecolloid and more particularly, to gelatin coating compositionsadvantageously adapted for use in connection with high-speed coatingmethods.

As is commonly recognized in the coatings industry, it is highlydesirable, if not essential, that water-permeable colloid, e.g.,gelatin, containing coating compositions be capable of applicationatrelatively high coating speeds, and that the layers so deposited be ofuniform and selected physical characteristics. The foregoingrequirements are of primary import in operations associated with thepreparation of photographic film elements. Ideally, coating aidscontemplated for use in water-permeable colloid-containing compositionsand especially those containing gelatin should:

I. Be of uniform quality, properties, etc. from batch to batch; i

2. Enable the use of high-speed coating operations both in wet-on-wetand wet-on-dry coatings;

3. Be devoid of any tendency to impart streakiness or repellency to thewater-permeable colloid;

4. Exhibit minimal sludge and/or foam formation;

5. Produce coatings having little or no tendency to slip;

6. Be nonphotoactive Heretofore, considerable difficulty has beenencountered in connection with attempts to provide water-permeablecolloid layers of the desired characteristics while utilizing coatingspeeds which are consonant with, feasible commercial operation andsatisfactory product throughput. With-gelatin compositions for example,and to which no auxiliary coating aid has been added, there areinvariably obtained coated layers whichexhibit manifold defectsincluding e.g., the presence of numerous crescent-shaped uncoated areas,also referred to as repellency spots, such defects approximating thesize of a pinhead with streaks or other such irregularities emanatingfrom the points of the crescent and proceeding in a direction oppositeto that of the coating. It isnot unusual to find that lightly coatedareas of 5-l0 mm. in diameter will result.

In an effort to overcome or otherwise mitigate the foregoing and relateddisadvantages, the art has resorted to the use of a wide variety ofcoating aids. Saponin for example despite its relatively widespread useas a coating aid in gelatin compositions of various types hasnevertheless proved somewhat unsatisfactory. Although yielding arelatively uniform and even coating, this material being of naturalorigin, may often vary markedly from batch to batch in quality,composition, purity and the like, to the extent that one v or more ofthe properties required in the photographic emulsion may bedeleteriously affected in the absence of'remed-ial proceduresdesigned'to compensate for such shortcomings e.g. the addition ofauxiliary ingredients which function to suppress or neutralize anyfugitive behavior of the coating aid.

As a consequence, considerable industrial attention has been focusedupon the development of synthetic-type coating aids selected from a widevariety of surfactant materials of the anionic, cationic and/or nonionictypes; representative co mpounds promulgated for such purposes include,for example, the taurides, betaines, imidazolinium salts, and the like.Since materials of the latter type may be subjected to relativelyprecise conditions of controlled manufacture, problems associated withvariations in quality, composition, purity and the like are minimized,if not completely eliminated. Despite the advantages accruing with theuse of the synthetic coating aids heretofore provided the results havenevertheless been unsatisfactory in a number of important respects. Asexamples of the more important difficulties repeatedly encountered withthe use of the latter materials and especially in connection with thepreparation of photographic layers containing gelatin, there may bementioned their tendency to produce streakiness and repellency spotsthat cannot be readily rewet with the consequent condition that theproduct tends to form air-bells" on the emulsion surface duringphotographic processing. Such areas will often manifest themselves inthe form of relatively small, undeveloped areas in the processed productdue to the fact that in such areas the developer is incapable ofpenetrating into the emulsion layer. These defects are not onlyunsightly to the extent that retouching of the negative is oftenrequired, but more importantly, can be dangerously misleading whenpresent on certain types of films particularly medical or industrialX-ray films.

The foregoing and related problems becomes increasingly manifest inconnection with wet-on-wet" coating methods wherein the water-permeablecolloid composition is applied to a wet substrate. The latter is, ofcourse, a matter of prime commercial importance andespecially inconnection with plural coating operations wherein it is of utmostimportance to eliminate any necessity for drying and thus the time'whichwould otherwise be consumed thereby.

However, with the use of the coating aids heretofore provided, the onepass-wet-on-wet" technique is found to be substantially inapplicable andaccordingly, it becomes necessary to dry an applied layer prior to theapplication of an additional layer.'The practical and economicdisadvantages thus accruing can be made readily manifest by thefollowing discus- .sion. In the manufacture of photographic filmelements comprising a film base coated with one or more light-sensitivelayers, e.g., gelatin-silver halide emulsion compositions, it isrecognized practice to include additional nonsensitized layers, e.g.,subbing, anticurl and anti-abrasion layers, for purposes of promotingstructural stability or otherwise augmenting those properties essentialto efficacious film usage and processing. Thus, it is conventionalpractice to provide a light-sensitive emulsion layer with a suitablesurface layer in order to preserve both the sensitivity as well asphysical characteristics of the emulsion layer as well as for insuringagainst the acquisition and retention of static electrical charge by thefilm element: Such surface layers are commonly referred to in the art asanti-abrasion antistatic layers, etc. Coating operations incident to theprovision of such layers usually involve the deposition of two or morehydrophilic colloid-containing layers, such as gelatin. Quite obviouslythe applicability of wet-on-wet coating techniques greatly facilitatesthe successive coating operations inherently involved. It has also beenobserved that those coating aids which to some extent permit the use ofwet-on-wet coating operations, albeit under rather stringent andpredetermined conditions, nevertheless prove in the vast majority ofinstances to be notoriously deficient when the coating method employedis of the high-speed type involving the air doctor technique.

Thus, a primary object of the present invention resides in the provisionof improved water-permeable colloid containing coating compositionswhich are substantially devoid of the above disadvantages.

Another object of the present invention resides in the provision ofimproved gelatin coating compositions advantageously adapted forapplication via the use of high speed coating techniques.

A further object of the present invention resides in the provision ofcoating aids for use with photosensitive gelatin emulsion compositionsto facilitate the attainment of coatings which are uniform andrepellency-free without deleteriously affecting the emulsion.

Other and related objects of the present invention will become apparenthereinafter as the description thereof proceeds.

The attainment of the foregoing and related objects is made possibleinaccordance with the present invention which, in its broader aspectsincludes the provision of improved waterpermeable colloid compositionscontaining as an essential ingredient a coating aid comprising apolyoxyalkylenated derivative of a primary monohydric saturatedaliphatic alcohol containing from eight to 10 carbon atoms said alcoholcontaining more than two alkyl side chains and having the molecularconfiguration of an alcohol produced by the 0x0 process from amono-olefinic hydrocarbon of seven to nine carbon atoms containing atleast two alkyl side chains said ether containing from two to 20oxyalkylene groups per mole. Thus, the compounds contemplated for useherein as coating aids may be represented according to the followingstructural formula:

wherein R represents alkyl containing from eight to ten carbon atomscontaining more than two alkyl side chains, X represents hydrogen ormethyl and n represents a positive integer of from two to inclusive.

The compounds encompassed by the above depicted structural formula aswell as methods for their preparation are described for example in U.S.Pat. No. 2,965,678. As explained therein, the oxo-alcohol employed as astarting material for polyoxyalkylation is prepared by the catalyticreaction of an olefin with carbon monoxide and hydrogen to form analdehyde, the latter being thereafter subjected to catalytic reductionwhereby to form the corresponding alcohol, such process being knowncommercially as the 0x0 process. The relatively specific and delimitedclass of polyoxyalkylenated oxo-alcohol compounds contemplated for usein accordance with the present invention embrace those compoundsprepared from mono-olefinic hydrocarbons containing from seven to ninecarbon atoms. As particular examples of branched chain primary aliphaticalcohols suitable for preparing the polyoxyalkylenated products of theabove formula there may be mentioned the following:

2,3,3-trimethyl-l-pentanol 2,2,3-trimethyl-l-pentanol2,3,4-trimethyl-l-pentanol 2,3,4,4-tetramethyl-l-pentanol2,3,5-trimethyl-l-hexanol 2,3,4,5-tetramethyl-l-hexanol2-methyl-3,4-diethyl-l-pentanol etc.

The starting alcohols employed in producing the compounds of thisinvention may be condensed with the required number of moles of ethyleneoxide or propylene oxide or a mixture of the two oxides in known manneraccording to the general methods illustrated in U.S. Pat. Nos. 1,970,578and 2,l74,76l, for example. The condensation is preferably carried outunder elevated temperatures and pressures and may be catalyzed byquaternary hydroxides, amines, or acidic and coordinating typecompounds, although the strong alkaline catalysts such as KOH or NaOHand the like are preferred because of the fewer by products formed andthe more easily controllable reaction conditions.

One of the truly surprising aspects to the discovery forming the basisof the present invention relates to the observation that the improvedcoating properties made possible are uniquely typical of thosepolyoxyalkylenated derivatives obtained with the C oxo-alcohols inparticular, i.e., to the exclusion of even closely related homologouscompounds. This seeming atypicality becomes even more acutely evidentwith high speed coating operations, i.e., the polyoxyalkylenatedderivatives of the C -C oxo-alcohols display a remarkable capacity toimpart optimum properties to the coating composition despite subjectionto coating speeds considerably in excess of those which may normally andefficaciously be used. Thus, it is found that the present inventionmakes possible the use of coating speeds up to 3 times thoseconventionally employed as a matter of necessity due to the inherentlimitations characterizing the coating aid compounds heretofore providedin the art. Moreover, coating compositions containing polyoxyalkylenatedderivatives of homologous oxo-alcohols are found to yield intolerablequantitles of repellency spots as well as other coating irregularitiesdespite the use of coating speeds which approximate but a fraction ofthose made possible by the present invention.

Although specific reference will be made to gelatin throughout thepresent description, the term water-permeable colloid as used herein isto be understood as encompassing water-soluble and/or dispersiblematerials whose aqueous solutions yield water-permeable films or drying.As examples of substances coming within this definition there may bementioned in particular and without limitation water-soluble celluloseesters of lactic or glycolic acid, partially hydrolyzed polyvinylacetate, modified polyvinyl alcohol, water-soluble polyvinyl acetals,etc. The colloid may also be suitably provided in the form of an aqueousdispersion, emulsion, suspension, etc., such as would be the case withpolymers derived from the polymerization of one or more acrylatemonomers, e.g., ethyl acrylate, methyl methacrylate, etc. The foregoingmaterials are conventionally provided in latex form by the use ofsuitable emulsifying agents, suspending agents or the like.

In accordance with the discovery forming the basis of the presentinvention, it has been ascertained that the improvements provided by theaforedescribed coating aids are obtained even though employed inrelatively small quantities, i.e., on the order of 0.0l percent andlower by weight based on the weight of the coating solution. it shouldbe understood, of course, that larger quantities may be employed toadvantage, for example, in amounts ranging up to 0.l percent and even 1percent by weight based on the weight of the coating solution. Theparticular proportions employed will, of course, depend primarily on theultimate use contemplated for the coating composition in question.Accordingly, the aforementioned concentrations are not particularlycritical but serve only to define those proportions found to yield, ingeneral, optimum results. For example, in those instances wherein thegelatin is to be incorporated directly into a photographic silver halideemulsion, the gelatin concentration will ordinarily range from about 2to about 10 percent by weight of the emulsion composition with a rangeof 6 to 8 percent being preferred. Accordingly, the amount ofpolyoxyalkylenated oxo-alcohol employed will ordinarily correspond to apreferred range of from about 0.l percent to about 5 percent by weightbased on the dry weight of the colloidal carrier material, e.g.,gelatin. Expressed in terms of coated area, the effective amounts ofcoating aids for use herein range from about 1 to about 50 milligramsper sq. ft. since 1 kilogram of gelatin, dry basis, will usually providecoverage for about l,000 sq. ft. of surface.

The photographic emulsions prepared utilizing the coating aids ofthepresent invention will ordinarily be comprised of an aqueous solution ofgelatin containing as the light-sensitive material a silver salt such assilver bromide, silver chloride, silver iodide as well as mixturesthereof. Such emulsions may be of the nonoptically sensitized,orthochromatic, panchromatic or X-ray type. When preparing thephotographic emulsion, the coating aid may be included either before orafter the addition of any of the other ingredients conventionallyemployed in gelatin-silver halide emulsions, e.g., sensitizing dyes,hardeners, etc. The particular coating procedure employed may compriseany of the standard methods well established in the coatings industry.For example, the substrate to be coated may be passed through a throughor other reservoir containing the coating solution. The coating may beapplied to greater thickness than desired ultimately and thereaftersubjected to the action of some leveling means such as a doctor blade oran air-brush which causes runback of the coating compositions therebyresulting in the obtention of an even surface. In some instances, thecoating method may involve a hopper technique in which the thickness ofthe layer is regulated by the rate at which the coating composition isdeposited upon the base which is transported in a direction adjacentthereto.

The following examples are given for purposes of illustrating thepresent invention and are not to be considered as being limitativethereof. In each of the examples, all parts given are by weight unlessotherwise indicated.

EXAMPLE I A silver halide photographic emulsion having a silverconcentration of approximately 35 grams per kilogram of emullOlOOR 0700sion and a gelatin concentration of approximately 70 grams per kilogramof emulsion is prepared. The emulsion is thereafter divided into fourparts identified as samples (a), (b), (c), and (d) respectively. Sample(a) serves as control. To sample (b) is added 0.0005 part of apolyethoxylated compound obtained by the, reaction of oxo-decanol with18 moles of ethylene oxide. To sample (c) is added 0.001 part of saponinas coating aid. To sample (cl) is added 0.0005 part of a polyethoxylatedmaterial obtained by the reaction of trimethyl nonanol with 6 moles ofethylene oxide. Each of the foregoing samples is thereafter coated ontoaphotographic cellulose acetate support via the air-doctor bladetechnique at a web speed of 120 ft. per minute. The quality of thecoating obtained is evaluated in terms of population density ofrepellencies per unit area. Within the context of the present invention,the term repellency" refers to uncoated areas whether in the form ofdots, lines or other irregularities. The results of the repellencyevaluations of each of the respective coated samples'are itemized in thefollowing table:

TABLE 1 Coating Aid Concentration/Unit Repellencies of Coating Solutionper 3 sq. ft.

(a) Control gross l0+ (b) Oxodecyl alcohol +l8 moles ethylene oxide0.0005 part None (c) Saponin 0.00 l part 3 (d) Trimethyl Nonanol +6moles ethylene oxide 0.0005 part 10+ Of special interest are the resultsobtained in connection "with sample (d) wherein the coating aidcomprises the reaction product of trimethyl nonanol with6 moles ofethylene oxide. As will be observed, this particular compound isascertained to be highly offensive in view of the rather high repellencydensity. Such compound deserves special mention since it comprises ahigher homolog to the compounds of the present invention, being preparedfrom a C primary aliphatic alcohol of the oxo-type. Despite the closesimilarity of such compound, the results make manifestly clear that arather remarkable improvement in thecapacity to impart optimum coatingproperties attends an even slight variation in the nature of the alcoholemployed. The trimethylnonanol derivative would, of course, be eminentlyunsuitable for use in the preparation of photographic elements intendedto provide a reliable an unimpeachable source of the informationreproduced i.e., critically dependent upon accuracy of reproduction aswould be the case for example with medical X-ray films due to the ratherhigh population density of repellencies. in fact, as the abovesummarized data clearly establishes the use of Saponin, albeit at asomewhat higher concentration, provides a final coating which isconsiderably superior to that obtained with the trimethyl nonanolderivative.

The following example illustrates the improvements obtainable when thecoating aid is included as an additive to a photographic silver halideemulsion layer, the latter serving as a support for a subsequentovercoating layer.

EXAMPLE 2 To a silver halide photographic emulsion identical with thatdescribed in example i is added 0.0005 part of the reaction productobtained by the condensation of oxodecyl alcohol with 18 moles ofethylene oxide. The coating solution thus obtained is coated onto acellulose acetate support of the type conventionally employed in thefabrication of photographic film elements, and chilled. Immediately uponcompletion of the chilling operation and without any drying, theemulsion layer is directly overcoated with a dilute, aqueous gelatinsolution which serves as an anti-abrasion layer. The anti-abrasion layeris applied at a web coating speed in excess of I20 ft. per minute.Despite the exceptionally high coating speed employed, there were noindications of skipping. By way of comparison, the procedure is repeatedwith an additional sample of the identical silver halide emulsioncomposition but containing Saponin as the coating aid in lieu of theethylene oxide/oxodecyl alcohol condensate. The overcoating operation iscarried out in identical fashion, i.e., the chilled emulsion layerwithout drying is overcoated with an aqueous, gelatin anti abrasioncomposition. However, in this instance, coating speeds of only 35-40 ft.per minute were permitted since coating speeds even slightly in excessof 40 ft. per minute, gave rise to severe skipping with the inevitableconsequencethat the coated layer exhibited an intolerably highpopulation density of repellencies. ln contradistinction, the use of theoxodecyl alcohol/ethylene oxide condensate makes possible the attainmentof a repellency-free anti-abrasion layer.

EXAMPLE 3 Example 2 is repeated except that the oxodecylalcohol/ethylene oxide condensate is replaced by an equivalent amount ofan oxo-nonyl alcohol/ethylene oxide (18 moles) condensate. The resultsobtained are similar to those described in example 2, i.e., theoxo-nonyl alcohol/ethylene oxide condensate makes possible theapplication of an antiabrasion surface layer totally devoid ofrepellencies.

EXAMPLE 4 Example 2 is repeated except that the oxodecylalcohol/ethylene oxide condensate is replaced with an equivalent amountof an oxo-octyl/ethylene oxide l 8 moles) condensate. The resultsobtained clearly establish the superiority of the coating aid of thepresent invention as regards the ability to permit the high-speeddeposition of gelatin surface layers to thereby provide arepellency-free coating.

Results similar to those described above are obtained when theprocedures described are repeated but employing in lieu of the specificcoating aids exemplified, polyether derivatives obtained by the reactionof a C -C oxo-alcohols with varying molar proportions of ethylene oxidewithin the range hereinbefore specified. Similar advantage likewiseattends the use of the polyoxypropylenated derivatives in lieu of thepolyoxyethylenated derivatives.

Improvements similar to those described aboveare further obtained whenthe gelatin carrier is replaced wholly or partly with one or more otherwater-permeable colloids such as the water-soluble cellulose esters oflactic or glycolic acid, partially hydrolyzed polyvinyl acetate,modified polyvinyl alcohol, water-soluble acetals, etc. I

in addition, it is found that gelatin coating compositions containingconventional coating aids of the type heretofore provided such as thetaurides, protein condensation products of fatty acids, saponin,polyoxyethylene derivatives of long chain fatty acids, alcohols, etc.,may be synergistically modified to advantage by including therein one ormore of the coating aids provided by the present invention. Moreover, inlieu of saponin, other suitable surface active agents may be added suchas sulfated oleic acid, dihexyl ester of sodium sulfosuccinate, sodiumsalt of an alkylnaphthalene sulfonic acid, sodium salt oftetrahydronaphthalene sulfonic acid, calcium glycerin phosphate,alkylphenylpolyethylene glycol, oleic acid ester of hydroxyethanesulfonic acid, and sulfonates of high molecular weight primary orsecondary aliphatic, aromatic and cycloaliphatic carboxy acids.

In addition, the improvements provided by the present invention are alsoobtained with silver halide emulsions which contain color formers whichare provided with a solubilizing sulfo or carboxy group, and therefore,soluble in alkali solutions, for instance, sodium hydroxide solutions.Such color formers which upon color development with a primary aminodeveloper yield azomethine, quinonimine or azine dyes, are described inUS. Pat. Nos. 2,186,734; 2,445,252; 2,530,349; 2,671,021; 2,524,725;2,354,552 and 2,547,037.

Furthermore the color coupler may be of the nondiffusing type which,when added to the silver halide emulsion dispersed in a mixture of highboiling and low boiling solvents, forms packet-type emulsions withcapsulated color formers. Such color formers are known to personsskilled in the art. Typical representatives are described in US. Pat.Nos. 2,186,852; 2,179,239; 2,179,244; 2,298,443; 2,369,489 and 2,511,231.

Although the present invention has been particularly described withreference to the preparation of photographic silver halide emulsions, itwill be understood that the coating compositions provided by the presentinvention may comprise simply a mixture of gelatin with one or more ofthe oxo-alcohol/alkylene oxide condensates. Such compositions findutility in a wide variety of applications and may be applied as such toany number of substrate materials for purposes of providing a suitableovercoat. For example, they may be employed to advantage as protectivecoatings for paper, plastics such as films of cellulose nitrate,cellulose esters, e.g., cellulose acetate, cellulose acetate butyrateand the like. In addition, they may be applied in the form ofantihalation layers, antistatic layers, filter layers or in any type ofgelatin layers which is coated from a composition consisting essentiallyof an aqueous solution of gelatin. For example, gelatin coatingcompositions intended for use as auxiliary layers, surface layers, etc.,will usually contain the gelatin in amounts approximating 2-3 percent byweight of the total composition. However, when employed in thepreparation of photographic emulsions, it is usually advisable to employlarger proportions of coating aid than would customarily be employed inaqueous solutions of gelatin intended for use as simple over coatings.Moreover, in some instances, it may be advantageous to employ largerproportions even though the coating composition in question is intendedfor use as a simple auxiliary, i.e., nonphotographic layer. For example,larger proportions of coating aid are found to permit the more effectiveuse of higher coating speeds. In

general, increased proportions of coating aid are usually desirablewhere the gelatin is employed in minor concentrations. The pl-[ of thecoating composition would ordinarily fall within a range of about 5 to8. For example, when utilizing the coating compositions described hereinas auxiliary layers, e.g., as a noncurling layer in a photographic filmelement, an acid pH range is usually preferred.

This invention has been described with respect to certain preferredembodiments and there will become obvious to persons skilled in the artother variations, modifications, and equivalents which are to beunderstood as coming within the scope of the present invention.

What is claimed is:

l. A noncolorforming coating composition comprising a water-permeablecolloid, and as a coating aid therein a polyoxyalkylene ether of aprimary monohydric saturated aliphatic alcohol of eight to 10 carbonatoms and containing a straight chain alkyl group of five to six carbonatoms carrying three or four methyl or ethyl side chains, said ethercontaining from two to 20 oxyalkylene groups per mole.

2. A composition according to claim 1 wherein said alcohol contains 10carbon atoms.

3. A composition according to claim 1 wherein said alcohol contains ninecarbon atoms.

4. A composition according to claim 1 wherein said alcohol containseight carbon atoms.

5. A composition according to claim 1 wherein said waterpermeablecolloid comprises gelatin.

6. A composition according to claim 5 wherein said gelatin comprises agelatin-silver halide photographic emulsion.

7. An article of manufacture comprising a support coated with thecomposition of claim 1.

8. An article of manufacture according to claim 7 wherein said supportcomprises cellulose acetate.

9. An article of manufacture comprising a support coated with thecomposition of claim 6.

10. An article of manufacture according to claim 9 wherein saidgelatin-silver halide emulsion layer is further overcoated with agelatin surface layer.

2. A composition according to claim 1 wherein said alcohol contains 10carbon atoms.
 3. A composition according to claim 1 wherein said alcoholcontains nine carbon atoms.
 4. A composition according to claim 1wherein said alcohol contains eight carbon atoms.
 5. A compositionaccording to claim 1 wherein said water-permeable colloid comprisesgelatin.
 6. A composition according to claim 5 wherein said gelatincomprises a gelatin-silver halide photographic emulsion.
 7. An articleof manufacture comprising a support coated with the composition ofclaim
 1. 8. An article of manufacture according to claim 7 wherein saidsupport comprises cellulose acetate.
 9. An article of manufacturecomprising a support coated with the composition of claim
 6. 10. Anarticle of manufacture according to claim 9 wherein said gelatin-silverhalide emulsion layer is further overcoated with a gelatin surfacelayer.